What is the correct spelling for FERRODX?

If you meant to type "ferrodx" but misspelled it, here are some possible correct suggestions. Perhaps you were referring to "ferrofluid", a magnetic fluid consisting of ferromagnetic particles that suspend in a liquid. Alternatively, you may have intended to write "ferroalloys", which are alloys of iron with other metals like chromium or nickel. Double-check and use the appropriate term in your context.